阅读说明：本技术 一种石墨基纳米复合材料双极板的制备工艺 (Preparation process of graphite-based nanocomposite bipolar plate ) 是由 林纪峰 袁佳林 于 2021-07-26 设计创作，主要内容包括：本发明属于双极板技术领域,具体涉及一种石墨基纳米复合材料双极板的制备工艺。本发明石墨基纳米复合材料双极板的制备工艺,包括制备碳纳米管-石墨烯杂化热固性树脂浆料、将碳纳米管-石墨烯杂化热固性树脂浆料、石墨粉及增强纤维制备块状模塑团料、以及对块状模塑团料模压得到石墨基纳米复合双极板的步骤,所述碳纳米管、石墨烯及增强纤维的加入量分别是石墨粉和热固性树脂浆料总重量的0.01%～10%、0.01%～10%及0.1%～15%。本发明的制备工艺通过引入碳纳米管、石墨烯和增强纤维,能够增强石墨基复合双极板的电性能与力学性能,制得的双极板兼具高导电性、高耐腐蚀性、优异的力学性能、超薄的厚度、优良的尺寸稳定性及耐高温性等优点。(The invention belongs to the technical field of bipolar plates, and particularly relates to a preparation process of a graphite-based nanocomposite bipolar plate. The preparation process of the graphite-based nanocomposite bipolar plate comprises the steps of preparing carbon nanotube-graphene hybrid thermosetting resin slurry, preparing bulk molding aggregate from the carbon nanotube-graphene hybrid thermosetting resin slurry, graphite powder and reinforcing fibers, and carrying out die pressing on the bulk molding aggregate to obtain the graphite-based nanocomposite bipolar plate, wherein the adding amounts of the carbon nanotube, the graphene and the reinforcing fibers are respectively 0.01-10%, 0.01-10% and 0.1-15% of the total weight of the graphite powder and the thermosetting resin slurry. According to the preparation process disclosed by the invention, the carbon nano tube, the graphene and the reinforcing fiber are introduced, so that the electrical property and the mechanical property of the graphite-based composite bipolar plate can be enhanced, and the prepared bipolar plate has the advantages of high conductivity, high corrosion resistance, excellent mechanical property, ultrathin thickness, excellent dimensional stability, high temperature resistance and the like.)

1. A preparation process of a graphite-based nanocomposite bipolar plate is characterized by comprising the following steps:

(1) adding carbon nanotubes and graphene into the prepared thermosetting resin slurry, and performing ultrasonic dispersion until the carbon nanotubes and the graphene are uniformly dispersed in the thermosetting resin slurry to obtain carbon nanotube-graphene hybrid thermosetting resin slurry;

(2) pouring the carbon nanotube-graphene hybrid thermosetting resin slurry obtained in the step (1), graphite powder and reinforcing fibers into a kneading machine for kneading and stirring to obtain a massive molding mass, and thickening and curing at room temperature;

(3) molding the block-shaped molding aggregate obtained in the step (2) at 50-250 ℃ and 5-50 MPa for 0.5-60 min to obtain a graphite-based nano composite bipolar plate;

the adding amount of the carbon nano tube, the graphene and the reinforcing fiber is 0.01-10%, 0.01-10% and 0.1-15% of the total weight of the graphite powder and the thermosetting resin slurry respectively.

2. The process for preparing a graphite-based nanocomposite bipolar plate according to claim 1, wherein said carbon nanotubes are multi-walled carbon nanotubes or single-walled carbon nanotubes.

3. The process for preparing a graphite-based nanocomposite bipolar plate according to claim 1, wherein the graphene is redox graphene, liquid phase exfoliated graphene, chemical vapor deposition graphene, or mechanical exfoliated graphene.

4. The preparation process of the graphite-based nanocomposite bipolar plate according to claim 1, wherein the reinforcing fibers are polyacrylonitrile-based carbon fibers or glass fibers, and the length of the reinforcing fibers is 0.02-10 mm.

5. The preparation process of the graphite-based nanocomposite bipolar plate according to claim 1, wherein the graphite powder is one or more of artificial graphite, natural flake graphite and expanded worm graphite, the particle size of the graphite powder is 1-1500 μm, and the amount of the graphite powder is 60-95% of the total weight of the graphite powder and the thermosetting resin slurry.

6. The process for preparing a graphite-based nanocomposite bipolar plate according to claim 1, wherein the preparation of the thermosetting resin slurry comprises the steps of:

stirring and mixing thermosetting resin, a low-shrinkage agent, a free radical initiator, a thickening agent, an internal release agent and a solvent in a dispersion machine at the speed of 2000-20000 r/min according to the required mass ratio to form thermosetting resin slurry, wherein the thermosetting resin is epoxy resin or vinyl ester resin;

the addition amounts of the low shrinkage agent, the free radical initiator, the thickening agent, the internal release agent and the solvent are respectively 5-25%, 1-10%, 5-35%, 1-14% and 5-20% of the weight of the thermosetting resin.

7. The process for preparing the graphite-based nanocomposite bipolar plate according to claim 6, wherein the epoxy resin is one or more of glycidyl ester epoxy resin, glycidyl amine epoxy resin and aliphatic cyclic epoxy resin;

the vinyl ester resin is one or more of epoxy vinyl ester resin, phenolic vinyl ester resin, vinyl ester resin homologue without styrene and phenolic epoxy modified vinyl ester resin.

8. The process for preparing a graphite-based nanocomposite bipolar plate according to claim 6, wherein the radical initiator is one or more of a peroxide, a hydroxide, a redox system, tert-butyl peroxybenzoate, a persulfate, and tert-butyl perbenzoate.

9. The process for preparing a graphite-based nanocomposite bipolar plate according to claim 6, wherein the internal mold release agent is calcium stearate or/and zinc stearate;

the thickening agent is one or more of magnesium oxide, calcium oxide, alkaline earth metal hydroxide and isocyanate;

the solvent is one or more of styrene monomer, alpha-methyl styrene monomer and methacrylate.

10. The process for preparing a graphite-based nanocomposite bipolar plate according to claim 6, wherein the low shrinkage agent is a styrene monomer-diluted polystyrene resin, a copolymer of styrene and acrylic acid copolymerization reaction, or a copolymer of vinyl acetate and acrylic acid copolymerization reaction.

Technical Field

The invention belongs to the technical field of bipolar plates, and particularly relates to a preparation process of a graphite-based nanocomposite bipolar plate.

Background

The bipolar plate is the heaviest and more costly component of the pem fuel cell, and represents about 80% and 40% of the total weight and cost of the fuel cell stack, respectively. Therefore, improving the mass, reducing the weight, and reducing the cost of pem fuel cells is a key to the development of pem fuel cells, particularly for automotive and mobile applications. The processing methods and materials used to manufacture the bipolar plates determine the final properties of the product.

Materials used to fabricate proton exchange membrane fuel cell bipolar plates include non-porous graphite, metallic materials, and polymer composites.

Graphite is the most commonly used material for fabricating proton exchange membrane fuel cells because of its excellent electrical properties as well as its excellent corrosion resistance. However, the graphite bipolar plate formed by machining in the market at present has poor mechanical properties, the yield is difficult to control, and the production period is long.

The metal bipolar plate has higher mechanical strength and electrical conductivity, and can be rapidly produced in large batch. However, the metal bipolar plate has poor corrosion resistance in the proton exchange membrane fuel cell, and metal ions are easy to separate out to cause catalyst poisoning and easily lose cell performance.

The current graphite bipolar plate is mostly formed into a flow channel of the cathode and anode bipolar plates by a mechanical processing and engraving mode. The graphite bipolar plate is limited by the cutting process, generally has very thick thickness, fussy processing process, low yield, higher cost and low mechanical strength, and is not beneficial to assembling the stack.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a preparation process of a graphite-based nanocomposite bipolar plate. The invention mainly aims to provide a preparation process of a graphite-based nanocomposite bipolar plate with high conductivity, high corrosion resistance, excellent mechanical property, ultrathin thickness, excellent dimensional stability and high temperature resistance.

In order to achieve the technical purpose, the embodiment of the invention adopts the technical scheme that: a preparation process of a graphite-based nanocomposite bipolar plate comprises the following steps:

(1) adding carbon nanotubes and graphene into the prepared thermosetting resin slurry, and performing ultrasonic dispersion until the carbon nanotubes and the graphene are uniformly dispersed in the thermosetting resin slurry to obtain carbon nanotube-graphene hybrid thermosetting resin slurry;

(2) pouring the carbon nanotube-graphene hybrid thermosetting resin slurry obtained in the step (1), graphite powder and reinforcing fibers into a kneading machine for kneading and stirring to obtain a massive molding mass, and thickening and curing at room temperature;

(3) molding the block-shaped molding aggregate obtained in the step (2) at 50-250 ℃ and 5-50 MPa for 0.5-60 min to obtain a graphite-based nano composite bipolar plate;

the adding amount of the carbon nano tube, the graphene and the reinforcing fiber is 0.01-10 percent, 0.01-10 percent and 0.1-15 percent of the total weight of the graphite powder and the thermosetting resin slurry respectively.

Further, the carbon nanotube is a multi-walled carbon nanotube or a single-walled carbon nanotube.

Further, the graphene is redox graphene, liquid phase-exfoliated graphene, chemical vapor deposition graphene or mechanically exfoliated graphene.

Further, the reinforcing fiber is polyacrylonitrile-based carbon fiber or glass fiber, and the length of the reinforcing fiber is 0.02-10 mm.

Further, the graphite powder is one or more of artificial graphite, natural crystalline flake graphite and expanded worm graphite, the particle size of the graphite powder is 1-1500 mu m, and the using amount of the graphite powder is 60-95% of the total weight of the graphite powder and the thermosetting resin slurry.

Further, the preparation of the thermosetting resin slurry comprises the following steps:

stirring and mixing thermosetting resin, a low-shrinkage agent, a free radical initiator, a thickening agent, an internal release agent and a solvent in a dispersion machine at the speed of 2000-20000 r/min according to the required mass ratio to form thermosetting resin slurry, wherein the thermosetting resin is epoxy resin or vinyl ester resin;

the addition amounts of the low shrinkage agent, the free radical initiator, the thickening agent, the internal release agent and the solvent are respectively 5-25%, 1-10%, 5-35%, 1-14% and 5-20% of the weight of the thermosetting resin.

Further, the epoxy resin is one or more of glycidyl ester epoxy resin, glycidyl amine epoxy resin and aliphatic ring epoxy resin;

the vinyl ester resin is one or more of epoxy vinyl ester resin, phenolic vinyl ester resin, vinyl ester resin homologue without styrene and phenolic epoxy modified vinyl ester resin.

Further, the free radical initiator is one or more of a peroxide, a hydroxide, a redox system, tert-butyl peroxybenzoate, a persulfate, and tert-butyl perbenzoate.

Further, the internal release agent is calcium stearate or/and zinc stearate;

the thickening agent is one or more of magnesium oxide, calcium oxide, alkaline earth metal hydroxide and isocyanate;

the solvent is one or more of styrene monomer, alpha-methyl styrene monomer and methacrylate.

Further, the low shrinkage agent is polystyrene resin diluted by styrene monomer, copolymer of styrene and acrylic acid copolymerization reaction or copolymer of vinyl acetate and acrylic acid copolymerization reaction.

Compared with the prior art, the invention has the following advantages:

according to the invention, the carbon nano tube and the graphene are mixed for use when the graphite-based nano composite bipolar plate is prepared to obtain the composite material, so that the mechanical property, the heat conduction property and the electrical property of the composite material can be better improved, and the carbon nano tube and the graphene have a certain synergistic effect when used simultaneously, the carbon nano tube can increase the interlayer spacing of the graphene, is more beneficial to the transfer of electrons, reduces the current percolation threshold of a polymer, has larger specific surface area and wrinkled surface texture characteristics, can form good interaction with the polymer and can be interlocked with a molecular chain of a polymer matrix, and greatly improves the toughness and the mechanical property of the polymer; the carbon nano tube with the one-dimensional structure and the graphene with the two-dimensional structure share the same structure, so that a three-dimensional network structure can be formed in a polymer, and the interaction with a polymer matrix can be better carried out. The introduction of the reinforcing fiber can improve the mechanical property and the chemical stability of the composite bipolar plate, and the reinforcing fiber can bear external load, so that the high specific strength and the specific rigidity of the bipolar plate are improved.

The carbon fiber or the glass fiber is used as the reinforcing fiber, wherein the carbon fiber is a high-performance fiber and has a series of excellent performances such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance and the like, so that the mechanical property of the composite material can be greatly improved. The glass fiber is an inorganic metal material with excellent performance, has the advantages of strong heat resistance, good corrosion resistance, high mechanical strength and the like, can enhance the rigidity and hardness of the composite material, improve the heat resistance and the thermal deformation temperature of the composite material, ensure the dimensional stability of the composite material and reduce the shrinkage rate.

According to the invention, the carbon nano tube, the graphene and the reinforcing fiber are introduced, so that the electrical property and the mechanical property of the graphite-based composite bipolar plate can be enhanced, graphite powder, thermosetting resin, the graphene, the carbon nano tube and the reinforcing fiber are mixed to form a massive molding material, and the massive molding material is subjected to one-step molding to prepare the ultrathin graphite-based nano composite bipolar plate, so that the proton exchange membrane fuel cell bipolar plate with high conductivity, high corrosion resistance, excellent mechanical property, ultrathin thickness, excellent dimensional stability and high temperature resistance is obtained.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

A preparation process of a graphite-based nanocomposite bipolar plate comprises the following steps:

(1) stirring and mixing 300g of epoxy vinyl ester resin, 15g of polystyrene resin (low shrinkage agent) diluted by styrene monomer, 15g of styrene monomer, 3g of tert-butyl peroxybenzoate as a free radical initiator, 20g of magnesium oxide as a thickening agent and 18g of calcium stearate as an internal release agent in a high-speed dispersion machine at the rotating speed of 3000r/min for 30min to form vinyl resin slurry, adding 8g of multi-walled carbon nanotube powder and 8g of redox graphene powder into the resin slurry, and performing ultrasonic dispersion treatment for 60min to uniformly disperse the multi-walled carbon nanotube powder and the redox graphene in the resin slurry to obtain multi-walled carbon nanotube-redox graphene hybrid vinyl resin slurry;

(2) pouring the multi-walled carbon nanotube-redox graphene hybrid vinyl resin slurry obtained in the step (1), 900g of graphite powder and 100g of glass fiber with the length of 6mm into a kneader, kneading and stirring for 1 hour to obtain a massive molding mass, and thickening for 72 hours at room temperature;

(3) and (3) separating and weighing the block molding compound cured in the step (2), wherein the preset temperature of the mold is 180 ℃, after the temperature reaches 180 ℃, the separated and weighed block molding compound is placed in the center of the mold, and is pressurized under the pressure of 30MPa to form a sample, after 8min, the mold is automatically opened by a press machine, and the sample is taken out, so that the graphite-based nanocomposite bipolar plate finished product is obtained.

The graphite powder is a mixture of natural crystalline flake graphite and expanded worm graphite, the natural crystalline flake graphite accounts for 90% of the total weight of the graphite powder, and the particle size of the natural crystalline flake graphite is 180-250 mu m; the expanded worm graphite accounts for 10% of the total weight of the graphite powder, and the particle size of the expanded worm graphite is 10-30 microns.

Example 2

A preparation process of a graphite-based nanocomposite bipolar plate comprises the following steps:

(1) stirring and mixing 300g of epoxy vinyl ester resin, 15g of polystyrene resin (low shrinkage agent) diluted by styrene monomer, 15g of styrene monomer, 3g of tert-butyl peroxybenzoate as a free radical initiator, 20g of magnesium oxide as a thickening agent and 18g of calcium stearate as an internal release agent in a high-speed dispersion machine at the rotating speed of 3000r/min for 30min to form vinyl resin slurry, adding 15g of multi-walled carbon nanotube powder and 15g of redox graphene powder into the resin slurry, and performing ultrasonic dispersion treatment for 60min to uniformly disperse the multi-walled carbon nanotube powder and the redox graphene in the resin slurry to obtain the multi-walled carbon nanotube-redox graphene hybrid vinyl resin slurry;

(2) pouring the multi-walled carbon nanotube-redox graphene hybrid vinyl resin slurry obtained in the step (1), 900g of graphite powder and 100g of glass fiber with the length of 6mm into a kneader, kneading and stirring for 1 hour to obtain a massive molding mass, and thickening for 72 hours at room temperature;

(3) and (3) separating and weighing the block molding compound cured in the step (2), wherein the preset temperature of the mold is 180 ℃, after the temperature reaches 180 ℃, the separated and weighed block molding compound is placed in the center of the mold, and is pressurized under the pressure of 30MPa to form a sample, after 8min, the mold is automatically opened by a press machine, and the sample is taken out, so that the graphite-based nanocomposite bipolar plate finished product is obtained.

The graphite powder is a mixture of natural crystalline flake graphite and expanded worm graphite, the natural crystalline flake graphite accounts for 90% of the total weight of the graphite powder, and the particle size of the natural crystalline flake graphite is 180-250 mu m; the expanded worm graphite accounts for 10% of the total weight of the graphite powder, and the particle size of the expanded worm graphite is 10-30 microns.

Example 3

A preparation process of a graphite-based nanocomposite bipolar plate comprises the following steps:

(1) stirring and mixing 300g of epoxy vinyl ester resin, 15g of polystyrene resin (low shrinkage agent) diluted by styrene monomer, 15g of styrene monomer, 3g of tert-butyl peroxybenzoate as a free radical initiator, 20g of magnesium oxide as a thickening agent and 18g of calcium stearate as an internal release agent in a high-speed dispersion machine at the rotating speed of 3000r/min for 30min to form vinyl resin slurry, adding 10g of multi-walled carbon nanotube powder and 10g of redox graphene powder into the resin slurry, and performing ultrasonic dispersion treatment for 60min to uniformly disperse the multi-walled carbon nanotube powder and the redox graphene in the resin slurry to obtain multi-walled carbon nanotube-redox graphene hybrid vinyl resin slurry;

(2) pouring the multi-walled carbon nanotube-redox graphene hybrid vinyl resin slurry obtained in the step (1), 900g of graphite powder and 200g of glass fiber with the length of 6mm into a kneader, kneading and stirring for 1 hour to obtain a massive molding mass, and thickening for 72 hours at room temperature;

(3) and (3) separating and weighing the block molding compound cured in the step (2), wherein the preset temperature of the mold is 180 ℃, after the temperature reaches 180 ℃, the separated and weighed block molding compound is placed in the center of the mold, and is pressurized under the pressure of 30MPa to form a sample, after 8min, the mold is automatically opened by a press machine, and the sample is taken out, so that the graphite-based nanocomposite bipolar plate finished product is obtained.

The graphite powder is a mixture of natural crystalline flake graphite and expanded worm graphite, the natural crystalline flake graphite accounts for 90% of the total weight of the graphite powder, and the particle size of the natural crystalline flake graphite is 180-250 mu m; the expanded worm graphite accounts for 10% of the total weight of the graphite powder, and the particle size of the expanded worm graphite is 10-30 microns.

Example 4

A preparation process of a graphite-based nanocomposite bipolar plate comprises the following steps:

(1) stirring and mixing 300g of glycidyl ester epoxy resin, 3g of a free radical initiator tert-butyl peroxybenzoate and 18g of an internal release agent calcium stearate in a high-speed dispersion machine at the rotating speed of 3000r/min for 30min to form epoxy resin slurry, adding 8g of multi-walled carbon nanotube powder and 8g of redox graphene powder into the resin slurry, and performing ultrasonic dispersion treatment for 60min to uniformly disperse the multi-walled carbon nanotube powder and the redox graphene in the resin slurry to obtain the multi-walled carbon nanotube-redox graphene hybrid epoxy resin slurry;

(2) pouring the multiwalled carbon nanotube-redox graphene hybrid epoxy resin slurry obtained in the step (1), 900g of graphite powder and 100g of glass fiber with the length of 6mm into a kneader, kneading and stirring for 1 hour to obtain a massive molding mass, and thickening for 72 hours at room temperature;

(3) and (3) separating and weighing the block molding compound cured in the step (2), wherein the preset temperature of the mold is 180 ℃, after the temperature reaches 180 ℃, placing the separated and weighed block molding compound in the center of the mold, pressurizing the block molding compound at the pressure of 30MPa to form a sample, automatically opening the mold by a press machine after 60min, and taking out the sample to obtain the graphite-based nanocomposite bipolar plate finished product.

The graphite powder is a mixture of natural crystalline flake graphite and expanded worm graphite, the natural crystalline flake graphite accounts for 90% of the total weight of the graphite powder, and the particle size of the natural crystalline flake graphite is 180-250 mu m; the expanded worm graphite accounts for 10% of the total weight of the graphite powder, and the particle size of the expanded worm graphite is 10-30 microns.

Comparative example 1

In this example, no redox graphene was added, and the remaining conditions were exactly the same as in example 1.

Comparative example 2

In this example, carbon nanotubes were not added, and the remaining conditions were exactly the same as in example 1.

Comparative example 3

In this example, no reinforcing fiber was added, and the other conditions were exactly the same as in example 1.

Comparative example 4

In this example, carbon nanotubes and redox graphene were not added, and the remaining conditions were exactly the same as in example 1.

The graphite-based nanocomposite bipolar plate products prepared in examples 1 to 4 and comparative examples 1 to 4 were compared in terms of their properties, and the results are shown in table 1:

table 1 comparison of the properties associated with the finished graphite-based nanocomposite bipolar plates of examples 1-4 and comparative examples 1-4

As can be seen from table 1, by comparing comparative example 1 with example 1, it can be seen that the volume conductivity and the bending strength of the graphite-based nanocomposite bipolar plate finished product prepared by adding the redox graphene are both improved, and especially the volume conductivity is obviously improved.

By comparing the comparative example 2 with the example 1, the volume conductivity and the bending strength of the finished product of the graphite-based nano composite bipolar plate prepared by adding the carbon nano tube are improved to a certain extent;

by comparing the comparative example 3 with the example 1, the addition of the reinforcing fibers can be seen, and the volume conductivity, the bending strength and the Shore hardness of the finished graphite-based nano composite bipolar plate are improved to a certain extent;

through comparison between comparative example 4 and example 1, it can be seen that the addition of redox graphene and carbon nanotubes both improve the bulk conductivity and bending strength of the finished graphite-based nanocomposite bipolar plate to a certain extent, and the omission of both redox graphene and carbon nanotubes in comparative example 4 results in a greater reduction in bulk conductivity and shore hardness of the bipolar plate, and the performance reduction is more significant compared to the omission of only redox graphene in comparative example 1 and the omission of only carbon nanotubes in comparative example 2, which indicates that the simultaneous use of redox graphene and carbon nanotubes improves the bulk conductivity of the bipolar plate to a greater extent, since the carbon nanotubes can increase the interlayer spacing of graphene when the carbon nanotubes are used in combination with graphene, is more beneficial to the transfer of electrons, and reduces the current percolation threshold of the polymer, the graphene has larger specific surface area and wrinkled surface texture characteristics, can form good interaction with the polymer and can be interlocked with a molecular chain of a polymer matrix, so that the toughness and the mechanical property of the polymer are greatly improved.

Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.